This present invention generally relates to techniques for optical switching. More particularly, the present invention provides a method and system for communicating between more than one optical switching systems, which are on a communication network. Merely by way of example, the invention is applied to a MEMS based switching system over a wide area network for long haul communications. But it would be recognized that the invention could also be applied to other types of switching such as wave guides, electro-optic devices, holographic switches, bubble switches, liquid crystal switches, and many others for applications including metropolitan, access, and other networks.
Over the past years, digital telephone has progressed with a desire for faster communication networks. In general, conventional analog voice telephone signals have been converted into digital signals. These signals can have transmission rates of 64,000 bits/second and greater in some applications. Other telephone circuits interleave these bit streams from 24 digitized phone lines into a single sequence of 1.5 Mbit/second, commonly called the T1 or DS1 rate. The T1 rate feeds into higher rates such as T2 and T3. A T4 may also be used. Single mode fiber optics has also been used at much higher speeds of data transfer. Here, optical switching networks have also been improved. An example of such optical switching standard is called the Synchronous Optical Network (SONET), which is a switching standard designed for telecommunications to use transmission capacity more efficiently than the conventional digital telephone hierarchy, which was noted above. SONET organizes data into 810-byte xe2x80x9cframesxe2x80x9d that include data on signal routing and designation as well as the signal itself. The frames can be switched individually without breaking the signal up into its components, but still require conventional switching devices.
Most of the conventional switching devices often require the need to convert optical signals from a first source into electric signals for switching such optical signals over a communication network. Once the electric signals have been switched, they are converted back into optical signals for transmission over the network. As merely an example, a product called the SN 16000, BroadLeaf(trademark) Network Operating System (NOS), made by Sycamore Networks, Inc. uses such electrical switching technique. Other systems have been developed by Lucent Technologies, Inc., Ciena Corporation, and other companies. Numerous limitations exist with such conventional electrical switching technique. For example, such electrical switching often requires a lot of complex electronic devices, which make the device difficult to scale. Additionally, such electronic devices become prone to failure, thereby influencing reliability of the network. The switch is also slow and is only as fast as the electrical devices. Accordingly, techniques for switching optical signals using a purely optical technology have been proposed. Such technology can use a wave guide approach for switching optical signals. Unfortunately, such technology has been difficult to scale and to build commercial devices.
Other companies have also been attempting to develop technologies for switching a high number of signals in other ways such as high density mirror arrays, but have been generally unsuccessful. A major obstacle for such high density mirror arrays is limited control software and complex system architecture. Conventional control software and the like have been developed for optical-to-electrical-to-optical switches. Such conventional software has been effective for controlling electrical communication signals. Additionally, such conventional software has not been implemented to communicate between more than one switching systems. Although effective for such electrical signals, they have limited applicability for optical communication signals and problems related thereto. Accordingly, such attempts have generally been unsuccessful.
From the above, it is seen that an improved way to communicate between optical switching systems is highly desirable.
According to the present invention, techniques including methods and systems for optical switching are provided. More particularly, the present invention provides a method and system for communicating between optical switching systems. Merely by way of example, the invention is applied to a MEMS based switching system over a wide area network for long haul communications. But it would be recognized that the invention could also be applied to other types of switching such as wave-guides, electro-optic devices, holographic switches, bubble switches, liquid crystal switches, and many others for applications including metropolitan, access, and other networks.
In a specific embodiment, the invention provides an optical system for switching one of a plurality of optical signals through a MEMS based cross-connect device. The system has first fiber input/output device and second fiber input/output device. An optical cross-connect device is coupled between the first fiber input/output device and the second fiber input/output device. A communication control device is adapted to identify a wavelength from either one of the first input/output device or the second fiber input/output device and selecting one of the first input/output devices for transmitting internal information to a second optical switch system.
In an alternative embodiment, the invention provides a method for communicating between at least two optical switching systems. Each of the optical switching systems includes an optical cross-connect coupled to an incoming fiber bundle and coupled to an outgoing fiber bundle. The method determines a control channel from a plurality of available channels. The plurality of available channels is provided on one or more optical fibers. The plurality of optical fibers are coupled between a first optical switch system and a second optical switch system. The method also opens an internal communication loop for the control channel between a first multiplexing device coupled to the first optical switch system and a second multiplexing device coupled to the second optical switch system. The method also includes forming a connection between the first optical switch system and the second optical switch system during a period of time that the internal communication loop has been opened. A step of maintaining the connection and transferring internal information between the first optical switch system and the second optical switch system also is included.
Many benefits are achieved by way of the present invention over conventional techniques. In some embodiments, the invention provides a way of communicating between two optical switching systems. Additionally, the invention provides a non-intrusive technique for communicating between such systems. In other aspects, the invention can be implemented using conventional hardware and/or software technologies. Depending upon the embodiment, one or more of these benefits may be achieved. These and other benefits will be described in more throughout the present specification and more particularly below.
Various additional objects, features and advantages of the present invention can be more fully appreciated with reference to the detailed description and accompanying drawings that follow.